Food Production

• Until approximately 1800 the world's population was relatively constant but since then it has increased rapidly
• The increasing human population requires an increased food yield
• Fertilisers


  Chemicals such as nitrates which increase crop yield
• Addition of fertilisers


  1. Nitrates dissolve in soil water and are absorbed by plants

  2. Plants use the nitrates to produce amino acids

  3. Animals consume plants or other animals to obtain amino acids for protein synthesis
• Fertilisers can leach into fresh water

  • Adding extra, unwanted nitrates
  • Increases algal populations which can cause algal blooms
  • Algal blooms reduce light levels, killing aquatic plants
  • Dead plants and algae become food for bacteria
  • Bacteria use up large quantities of oxygen, reducing the oxygen availability for other organisms
• Pesticides


  Chemicals which kill plants and animals which reduce crop yield
• Pesticides sprayed onto crops can accumulate in the bodies of organisms over time


  • As they are passed along food chains, toxicity increases and can reach lethal levels
  • This build up of toxic substances in living organisms is known as bioaccumulation
• Genetically modified (GM) crops

  • Plants where a gene from another organism has been transferred into its DNA to give it a new characteristic
  • These genes may make the plant less likely to need fertilisers or pesticides to help it grow
• Biological control


  • A method of controlling that relies on the introduction of natural predators rather than toxic chemicals
  • Can be used as an alternative to pesticides
• Increased food yield


  The amount of food produced, with more needed to meet the demands of a growing population
• Nitrates


  A form of nitrogen that plants can easily absorb and use for growth. Commonly found in soil and produced naturally by the breakdown of organic matter.
• Ammonia


  A gas that can be converted into a form that plants can use, such as ammonium (NH4+). However, ammonia can be toxic to plants in high concentrations.
• DNA


  Genetic material present in every cell of an organism, containing the instructions for its development and function. In GM crops, a gene from another organism is transferred into its DNA to give it a new characteristic.
• Proteins


  Large complex molecules that perform various functions within organisms, such as catalyzing metabolic reactions, DNA replication, responding to stimuli, and transporting molecules. In GM crops, the new gene introduced into the plant's DNA may code for a specific protein that provides the plant with a new characteristic.